Bioinspired Multifunctional Self-Sensing Actuated Gradient Hydrogel for Soft-Hard Robot Remote Interaction

The development of bioinspired gradient hydrogels with self-sensing actuated capabilities for remote interaction with soft-hard robots remains a challenging endeavor. Here, we propose a novel multifunctional self-sensing actuated gradient hydrogel that combines ultrafast actuation and high sensitivity for remote interaction with robotic hand. The gradient network structure, achieved through a wettability difference method involving the rapid precipitation of MoO_(2) nanosheets, introduces hydrophilic disparities between two sides within hydrogel. This distinctive approach bestows the hydrogel with ultrafast thermo-responsive actuation(21° s^(-1)) and enhanced photothermal efficiency(increase by 3.7 ℃ s^(-1) under 808 nm near-infrared). Moreover, the local cross-linking of sodium alginate with Ca^(2+) endows the hydrogel with programmable deformability and information display capabilities. Additionally, the hydrogel exhibits high sensitivity(gauge factor 3.94 within a wide strain range of 600%), fast response times(140 ms) and good cycling stability. Leveraging these exceptional properties, we incorporate the hydrogel into various soft actuators, including soft gripper, artificial iris, and bioinspired jellyfish, as well as wearable electronics capable of precise human motion and physiological signal detection. Furthermore, through the synergistic combination of remarkable actuation and sensitivity, we realize a self-sensing touch bioinspired tongue. Notably, by employing quantitative analysis of actuation-sensing, we realize remote interaction between soft-hard robot via the Internet of Things. The multifunctional self-sensing actuated gradient hydrogel presented in this study provides a new insight for advanced somatosensory materials, self-feedback intelligent soft robots and human–machine interactions.

Magnetic Interactions with Strain Gradient in Ultrathin Pr_(0.67)Sr_(0.33)MnO_(3) Films

Strain gradient is a normal phenomenon around a heterostructural interface in ultrathin film,and it is important to determine its effect on magnetic interactions to understand interfacial coupling.In this work,ultrathin Pr_(0.67)Sr_(0.33)MnO_(3)(PSMO)films on different substrates are studied.For PSMO film under different in-plane strain conditions,the saturated magnetization and Curie temperature can be qualitatively explained by double-exchange interaction and the Jahn-Teller distortion.However,the difference in the saturated magnetization with zero field cooling and 5 T field cooling is proportional to the strain gradient.Strain-gradient-induced structural disorder is proposed to enhance phonon-electron antiferromagnetic interactions and the corresponding antiferromagnetic-to-ferromagnetic phase transition via a strong magnetic field during the field cooling process.A non-monotonous structural transition of the MnO_(6) octahedral rotation can enlarge the strain gradient in PSMO film on a SrTiO_(3) substrate.This work demonstrates the existence of the flexomagnetic effect in ultrathin manganite film,which should be applicable to other complex oxide systems.

Gradient structure induced simultaneous enhancement of strength and ductility in AZ31 Mg alloy with twin-twin interactions

Gradient nanostructure was introduced to enhance the strength and ductility via deformation incompatibility accommodated by geometrical necessary dislocations for most metallic materials recently.However,few intensive researches were carried out to investigate the effect of gradient structure on the deformation twin evolution and resulting performance improvements.In the present paper,we produced gradient-structured AZ31 Mg alloy with fine-grain layers,parallel twin laminates and a coarse-grain core from two upmost surfaces to the center of plate.Surprisingly,this architected Mg alloy exhibited simultaneous enhancement of strength and ductility.Subsequent microstructural observations demonstrated that abundant twin-twin interactions resulting from higher strength and multi-axial stress state could make great contributions to the increase of work-hardening capability.This was further proved by the measurement of full-field strain evolution during the plastic deformation.Such a design strategy may provide a new path for producing advanced structure materials in which the deformation twinning works as one of the dominant plasticity mechanisms.

A Perspective on the Evolution of Atmospheric Blocking Theories:From Eddy-Mean flow Interaction to Nonlinear Multiscale Interaction

In this paper,we first review the research advancements in blocking dynamics and highlight the merits and drawbacks of the previous theories of atmospheric blocking.Then,the dynamical mechanisms of atmospheric blocking are presented based on a nonlinear multi-scale interaction(NMI)model.Previous studies suggested that the eddy deformation(e.g.,eddy straining,wave breaking,and eddy merging)might lead to the formation and maintenance of atmospheric blocking.However,the results were speculative and problematic because the previous studies,based on the time-mean eddy-mean flow interaction model,cannot identify the causal relationship between the evolution of atmospheric blocking and the eddy deformation.Based on the NMI model,we indicate that the onset,growth,maintenance,and decay of atmospheric blocking is mainly produced by the spatiotemporal evolution of pre-existing upstream synoptic-scale eddies,whereas the eddy deformation is a concomitant phenomenon of the blocking formation.The lifetime of blocking is mainly determined by the meridional background potential vorticity gradient(PVy)because a small PVyfavors weak energy dispersion and strong nonlinearity to sustain the blocking.But the zonal movement of atmospheric blocking is associated with the background westerly wind,PVy,and the blocking amplitude.Using this NMI model,a bridge from the climate change to sub-seasonal atmospheric blocking and weather extremes might be established via examining the effect of climate change on PVy.Thus,it is expected that using the NMI model to explore the dynamics of atmospheric blocking and its change is a new direction in the future.

Conjugate Gradient Method to Solve Fluid Structure Interaction Problem

In this paper, we propose a method to solve coupled problem. Our computational method is mainly based on conjugate gradient algorithm. We use finite difference method for the structure and finite element method for the fluid. Conjugate gradient method gives suitable numerical results according to some papers.

Mechanical characteristic variation of ballastless track in highspeed railway:effect of train–track interaction and environment loads

Due to the fact that ballastless tracks in highspeed railways are not only subjected to repeated train–track dynamic interaction loads,but also suffer from complex environmental loads,the fundamental understanding of mechanical performance of ballastless tracks under sophisticated service conditions is an increasingly demanding and challenging issue in high-speed railway networks.This work aims to reveal the effect of train–track interaction and environment loads on the mechanical characteristic variation of ballastless tracks in high-speed railways,particularly focusing on the typical interface damage evolution between track layers.To this end,a finite element model of a double-block ballastless track involving the cohesive zone model for the track interface is first established to analyze the mechanical properties of the track interface under the loading–unloading processes of the negative temperature gradient load(TGL)followed by the same cycle of the positive TGL.Subsequently,the effect of wheel–rail longitudinal interactions on the nonlinear dynamic characteristics of the track interface is investigated by using a vehicle-slab track vertical-longitudinal coupled dynamics model.Finally,the influence of dynamic water pressure induced by vehicle dynamic load on the mechanical characteristics and damage evolution of the track interface is elucidated using a fluid–solid coupling method.Results show that the loading history of the positive and negative TGLs has a great impact on the nonlinear development and distribution of the track interface stress and damage;the interface damage could be induced by the wheel–rail longitudinal vibrations at a high vehicle running speed owing to the dynamic amplification effect caused by short wave irregularities;the vehicle dynamic load could produce considerable water pressure that presents nonlinear spatial–temporal characteristics at the track interface,which would lead to the interface failure under a certain condition due to the coupled dynamic effect of vehicle load and water pressure.

Study on climate-vegetation interaction in China

The climate-vegetation interaction of China is mainly controlled by the atmospheric circulations and topographic characteristics. The distribution and NPP of vegetation zones show a close relationship with a series of climatological indexes, such as annual mean temperature, precipitation, various thermal indexes, and potential evapotranspiration rates. The multivariate analysis (DCA) for climate and vegetation, zones in China provides quantitative environmental interpretation for two significant ecological gradients. The first gradient is mainly a thermal gradient, it can be displayed by latitude, altitude, biotemperature, and annual mean temperature. The second gradient is basically a moisture gradient, it correlated highly with longitude and potential evaportranspiration. The quantitative interaction or statistical models between vegetation zones and climato-geographical indexes can provide a fundamental scenario and comparative parameters for the study on climate and vegetation changes in China.

草原灌丛化过程灌木-草本植物相互作用研究进展

近年来,草原生态系统发生剧烈变化,灌丛化现象加剧。草原灌丛化的本质是灌木-草本植物相互作用的方向与强度发生改变,从而引起群落结构的变化。本文从灌木-草本植物相互作用的主要影响因素、发生机制及其对群落演替的影响三方面梳理近年研究进展,探讨各种环境因素影响下灌木-草本植物相互作用的变化趋势及其对草原群落的影响,以期为全球气候变化背景下灌木-草本植物动态变化及灌丛化草原群落演替方向预测提供参考,也为我国灌丛化草原的恢复与管理提供理论依据。

温度梯度相互作用色谱在聚烯烃表征中的应用

研究了高温-温度梯度相互作用色谱(HT-TGIC)在聚烯烃表征中的应用,并与结晶分级技术进行了对比,同时分析了实验条件对HT-TGIC曲线的影响。实验结果表明,相比结晶分级技术,HT-TGIC在表征结晶度较低或完全无定形树脂时具有明显优势。HT-TGIC可用于定量表征聚烯烃树脂及其共混物的化学组成分布,并具有良好分辨率。优化的操作条件为:尽可能快的冷却速度、升温速率/淋洗流量的比值在一定范围内、动态降温、较小的动态吸附流量、冷却循环最终温度高于结晶温度。利用辛烯含量差与HT-TGIC淋洗峰偏离值呈线性关系,可快速确定共聚单体含量,包括高共聚单体含量树脂。

重力场诱导质量浓度梯度构筑各向异性水凝胶

文章采用N,N-双(丙烯酰)胱胺(BACA)修饰银纳米线(AgNWs)作为多功能大分子交联剂和导电填料,以丙烯酸钠为离子型可聚合单体,重力场作用诱导多功能大分子交联剂组装形成质量浓度梯度,在催化剂和热引发条件下发生自由基聚合反应,制备基于质量浓度梯度的高度各向异性纳米复合水凝胶。通过扫描电子显微镜(scanning electron microscope,SEM)、透射电子显微镜(transmission electron microscope,TEM)、万能材料测试仪、电化学工作站、红外热像仪等对所制备的纳米复合水凝胶进行表征,结果表明,该纳米复合水凝胶网络密度自上而下逐级提高,表现出高度各向异性的机械、电学、光热等行为。通过对其相关性能的检测,结果表明,该纳米复合水凝胶可以快速地在水条件和近红外辐照下发生不对称形状变化,在柔性智能驱动领域有着广阔的应用前景。

Impact of the Spring SST Gradient between the Tropical Indian Ocean and Western Pacific on Landfalling Tropical Cyclone Frequency in China

The present study identifies a significant influence of the sea surface temperature gradient（SSTG） between the tropical Indian Ocean（TIO; 15°S-15°N, 40°-90°E） and the western Pacific warm pool（WWP; 0°-15°N, 125°-155°E） in boreal spring on tropical cyclone（TC） landfall frequency in China's Mainland in boreal summer. During the period 1979-2015, a positive spring SSTG induces a zonal inter-basin circulation anomaly with lower-level convergence, mid-tropospheric ascendance and upper-level divergence over the west-central TIO, and the opposite situation over the WWP, which produces lower-level anomalous easterlies and upper-level anomalous westerlies between the TIO and WWP. This zonal circulation anomaly further warms the west-central TIO by driving warm water westward and cools the WWP by inducing local upwelling, which facilitates the persistence of the anomaly until the summer. Consequently, lower-level negative vorticity, strong vertical wind shear and lower-level anticyclonic anomalies prevail over most of the western North Pacific（WNP）, which decreases the TC genesis frequency. Meanwhile, there is an anomalous mid-tropospheric anticyclone over the main WNP TC genesis region,meaning a westerly anomaly dominates over coastal regions of China's Mainland, which is unfavorable for steering TCs to make landfall in China's Mainland during summer. This implies that the spring SSTG may act as a potential indicator for TC landfall frequency in China's Mainland.

On band gaps of nonlocal acoustic lattice metamaterials:a robust strain gradient model

We have proposed an"exact"strain gradient(SG)continuum model to properly predict the dispersive characteristics of diatomic lattice metamaterials with local and nonlocal interactions.The key enhancement is proposing a wavelength-dependent Taylor expansion to obtain a satisfactory accuracy when the wavelength gets close to the lattice spacing.Such a wavelength-dependent Taylor expansion is applied to the displacement field of the diatomic lattice,resulting in a novel SG model.For various kinds of diatomic lattices,the dispersion diagrams given by the proposed SG model always agree well with those given by the discrete model throughout the first Brillouin zone,manifesting the robustness of the present model.Based on this SG model,we have conducted the following discussions.(Ⅰ)Both mass and stiffness ratios affect the band gap structures of diatomic lattice metamaterials,which is very helpful for the design of metamaterials.(Ⅱ)The increase in the SG order can enhance the model performance if the modified Taylor expansion is adopted.Without doing so,the higher-order continuum model can suffer from a stronger instability issue and does not necessarily have a better accuracy.The proposed SG continuum model with the eighth-order truncation is found to be enough to capture the dispersion behaviors all over the first Brillouin zone.(Ⅲ)The effects of the nonlocal interactions are analyzed.The nonlocal interactions reduce the workable range of the well-known long-wave approximation,causing more local extrema in the dispersive diagrams.The present model can serve as a satisfactory continuum theory when the wavelength gets close to the lattice spacing,i.e.,when the long-wave approximation is no longer valid.For the convenience of band gap designs,we have also provided the design space from which one can easily obtain the proper mass and stiffness ratios corresponding to a requested band gap width.

An All‑In‑One Multifunctional Touch Sensor with Carbon‑Based Gradient Resistance Elements

Human–machine interactions using deep-learning methods are important in the research of virtual reality,augmented reality,and metaverse.Such research remains challenging as current interactive sensing interfaces for single-point or multipoint touch input are trapped by massive crossover electrodes,signal crosstalk,propagation delay,and demanding configuration requirements.Here,an all-inone multipoint touch sensor(AIOM touch sensor)with only two electrodes is reported.The AIOM touch sensor is efficiently constructed by gradient resistance elements,which can highly adapt to diverse application-dependent configurations.Combined with deep learning method,the AIOM touch sensor can be utilized to recognize,learn,and memorize human–machine interactions.A biometric verification system is built based on the AIOM touch sensor,which achieves a high identification accuracy of over 98%and offers a promising hybrid cyber security against password leaking.Diversiform human–machine interactions,including freely playing piano music and programmatically controlling a drone,demonstrate the high stability,rapid response time,and excellent spatiotemporally dynamic resolution of the AIOM touch sensor,which will promote significant development of interactive sensing interfaces between fingertips and virtual objects.

Changes in ecological stoichiometry and nutrient resorption in Castanopsis hystrix plantations along an urbanization gradient in the lower subtropics

The stoichiometry of carbon,nitrogen and phosphorous in plants can reflect the interactions between plants and their environment.The interplay between plant nutrients,climatic factors,and soil properties and the underlying regulatory mechanisms are pillars of ecology but remain underexplored.In this study of plant C-N-P stoichiometry and nutrient resorption in Castanopsis hystrix groves in three cities(Guangzhou,Zhongshan,and Lechang)that represent an urban-rural gradient in Guangdong Province,South China,we explored potential relationships among NO_(2) concentrations,diameter at breast height(DBH),and resident human population.Mean annual temperature,mean annual precipitation,insolation duration per year,and the human resident population differed significantly among the three cities.Soil C-N-P was always highest in suburban Lechang,and the concentration of NO_(2) was highest in urban Guanghzou(55.33±0.67μg m^(-3))and positively correlated with the resident population and leaf N:P.Our findings suggest that C-N-P stoichiometry of C.hystrix was better explained by NO_(2)than by soil C-N-P stoichiometry and that nutrient resorption was better explained by leaf nutrients and DBH than by NO_(2) and soil stoichiometry.Our study supports the hypothesis that rapid urbanization influences NO_(2) concentrations and microclimate,which may jointly change the stoichiometry of plant nutrients in the forest ecosystems.

Effects of substrate-ion density gradients on light-ion acceleration from ultraintense laser pulse irradiated thin-foils

A general solution of the electrostatic potential that determines the maximum light-ion energy is derived for the test-particle acceleration model by taking into account the influence of the substrate-ion density gradient. It is shown that the substrate-ion density structure is also dependent on laser pulse duration. In the picosecond or sub-picosecond regime, the decreasing density gradient of the substrate-ions leads to an evident reduction in the acceleration efficiency of the light-ions. However, this kind of influence is negligible in the ultrashort regime.

A size-gradient hypothesis for alpine treeline ecotones

Research on the stress gradient hypothesis recognizes that positive(i.e. facilitative) and negative(i.e. competitive) plant interactions change in intensity and effect relative to abiotic stress experienced on a gradient. Motivated by observations of alpine treeline ecotones, we suggest that this switch in interaction could operate along a gradient of relative size of individual plants. We propose that as neighbors increase in size relative to a focal plant they improve the environment for that plant up to a critical point. After this critical point is surpassed, however, increasing relative size of neighbors will degrade the environment such that the net interaction intensity becomes negative. We developed a conceptual(not site or species specific) individual based model to simulate a single species with recruitment, growth, and mortality dependent on the environment mediated by the relative size of neighbors. Growth and size form a feedback. Simulation results show that the size gradient model produces metrics similar to that of a stress gradient model. Visualizations reveal that the size gradient model produces spatial patterns that are similar to the complex ones observed at alpine treelines. Size-mediated interaction could be a mechanism of the stress gradient hypothesis or it could operate independent of abiotic stress.

动态视觉对城市视线通廊影响机制与模型调控

当前,我国城市空间整体协同性差、景观秩序紊乱等城市失控表征凸显。动态视线通廊模型分析法缺失导致视觉景观控制系统无法满足城市多模态交通环境的需求,甚至陷入建设性破坏的窘境。探究动态视知觉对视线通廊影响机制已迫在眉睫。历经十年研究发现:动态视功能在城市快行交通景观管控体系中具有关键调节作用。运用人机交互技术进行数据采集,获取隧道视觉梯度缩减率参数变量,推演动态条件的椭圆截面视锥3D空间域、景观控制界面2D视域和圈层式景观协控指标,构建数理模型,揭示动态视觉对景观视觉线性空间影响的科学本源,阐明城市形态的协调共生机制,探寻城市区块的和谐发展策略,为我国城市政策制定和实施管控,提供理论依据与技术支持。

不同海拔百山祖冷杉细根性状及微生物群落组成

研究植物性状及与植物密切相关的微生物群落沿海拔的变异,有助于理解个体对环境变化的适应能力。以生存于不同海拔高度的极小种群野生植物百山祖冷杉(Abies beshanzuensis)成年个体(海拔951、1400和1590 m处为人工培育实生苗,海拔1750m处为野生成年个体)为研究对象,利用根系扫描仪测定百山祖冷杉细根性状,利用高通量测序技术分析百山祖冷杉根际土壤及根内微生物(细菌及真菌)群落组成,探究根际土壤及根内微生物群落和细根性状在不同海拔高度的差异。结果表明:不同海拔高度的百山祖冷杉周围土壤养分有效性较差,理化性质除铵态氮含量和pH值外均存在显著差异(P<0.05)。根际土壤及根内真菌和细菌群落沿海拔变异明显。为适应土壤生物及非生物因子沿海拔的变化,百山祖冷杉采取不同的细根营养策略,细根具有高度可塑性,与外生菌根真菌产生协同效应缓解了百山祖冷杉受到的生存限制。

基于深度多任务学习的图像美感与情感联合预测研究

图像美学评价和情感分析任务旨在使计算机可以辨认人类由受到图像视觉刺激而产生的审美和情感反应.现有研究通常将它们当作两个相互独立的任务.但是,人类的美感与情感反应并不是孤立出现的;相反,在心理认知层面上,两种感受的出现应是相互关联和相互影响的.受此启发,采用深度多任务学习方法在统一的框架下处理图像美学评价和情感分析任务,深入探索两个任务间的内在关联.具体来说,提出一种自适应特征交互模块将两个单任务的基干网络进行关联,以完成图像美学评价和情感分析任务的联合预测.该模块中引入了一种特征动态交互机制,可以根据任务间的特征依赖关系自适应地决定任务间需要进行特征交互的程度.在多任务网络结构的参数更新过程中,根据美学评价与情感分析任务的学习复杂度和收敛速度等差异,提出一种任务间梯度平衡策略,以保证各个任务可以在联合预测的框架下平衡学习.此外,构建了一个大规模的图像美学情感联合数据集UAE.据已有研究,该数据集是首个同时包含美感和情感标签的图像集合.本模型代码以及UAE数据集已经公布在https://github.com/zhenshen-mla/Aesthetic-Emotion-Dataset.

沿干旱梯度小叶锦鸡儿灌丛化对草本植物叶片矿质元素浓度及地上生物量累积的影响

草原灌丛化通过改变物种之间的相互作用深刻影响着群落的结构和功能。然而,当前有关灌木如何影响不同功能群草本植物对矿质元素吸收和累积的研究仍明显不足。在内蒙古草原沿干旱梯度选取了4个研究地点,对比分析了小叶锦鸡儿(Caragana microphylla)灌丛斑块内和斑块外群落中禾草和非禾草功能群植物叶中矿质元素浓度以及地上生物量生产的差异,旨在阐明干旱和灌木对群落草本植物叶元素累积的影响,揭示灌草间相互作用的元素利用特征及其随干旱梯度的变化。结果显示:1)随干旱加剧,灌丛斑块内的非禾草功能群植物地上生物量保持恒定,但叶中的K、Ca、Mg、Fe、Mn和Cu元素浓度显著增加(P<0.05)。该结果表明群落中的非禾草功能群植物通过提高叶中的矿质元素水平来抵御和适应干旱胁迫。2)随干旱加剧,灌丛对非禾草功能群植物地上生物量,叶中Ca、Fe、Cu和Zn,禾草功能群植物叶中的P的累积影响从负(RII<0)或中性(RII=0)转变为正效应(RII>0)。该结果与胁迫梯度假说相符,表明灌木对草本植物的促进效应随干旱胁迫加剧而增加。3)灌丛的“沃岛”效应是驱动灌木对草本植物元素累积正效应的主要机制。研究结果揭示了锦鸡儿属灌木的促进效应在维持内蒙古干旱、半干旱草原群落植被物种共存和生态系统功能稳定中的重要性。